Pothos

@drzl/generator-pothos emits a Pothos schema builder from your Drizzle schema: one object type per table, each checked against the row type it came from.

Why this and not the SDL

DRZL already emits GraphQL SDL. SDL is a string. It describes a schema and cannot be extended, so a resolver written against it is checked by nothing: return the wrong shape, misspell a field, and you find out at runtime.

A Pothos builder is code. t.exposeString('emial') is a compile error here, and silently returns undefined from a hand-written resolver against SDL. That is the whole reason to emit one.

The two generators agree exactly on which GraphQL type each column gets, deliberately: the same column described two ways by two DRZL generators is worse than either description on its own.

Setup

// drzl.config.ts
export default {
  schema: './src/db/schema.ts',
  generators: [{ kind: 'pothos', path: 'src/graphql' }],
};

npm install -D @drzl/generator-pothos
npm install @pothos/core graphql

Like the seed and fast-check generators, this reads nothing from a validation generator. The object types are checked against row interfaces it writes itself.

What is emitted

• builder.ts holds the builder and a Row interface per table. One module, not one per table, because SchemaBuilder<{ Objects: ... }> names every type in a single generic: split up, each object module would import the builder and the builder would import each row type, which is a cycle.
• One module per table, calling builder.objectType('Users', { fields: ... }).
• index.ts pulls them in, adds a query field per table and calls builder.toSchema().

import { schema } from './graphql';

Nullability is stated on every field, and that is not verbosity

Pothos defaults every field to nullable. A NOT NULL column written as a bare t.exposeString('email') reaches clients as String, and every one of them null-checks a field that cannot be null.

The obvious fix is defaultFieldNullability: false on the builder. It does not compile:

error TS2353: Object literal may only specify known properties, and
'defaultFieldNullability' does not exist in type 'RemoveNeverKeys<SchemaBuilderOptions<...>>'

That option is legal only on a builder with no type parameter, which runs in Pothos's v3 compatibility mode. On a v4 generic, which is what a generated builder is, it types as never, because there it exists only to opt into nullable. Removing it and running the schema shows the runtime default is nullable in both shapes, so the central switch is unavailable exactly where it would be useful.

So every field says which it is:

email: t.exposeString('email', { nullable: false }),
bio: t.exposeString('bio', { nullable: true }),

A reader sees a column's nullability without knowing anything about the builder, which is worth the extra words on its own.

Scalars

Column	GraphQL	Why
bounded int32	Int	Only where declared bounds prove 32 bits
other numbers	Float	graphql-js refuses 2^31, so an unbounded integer must not be Int
uuid	ID
Date	DateTime	A registered scalar, ISO 8601 in UTC
bigint	BigInt	A registered scalar, decimal digits as a string
json	JSON	A registered scalar, passed through

BigInt travels as a string because JSON.stringify(1n) throws and a number loses precision past 2^53. The scalars are written into the emitted tree rather than pulled from graphql-scalars, which would be a dependency for three short definitions.

An enum column is a String rather than a GraphQL enum, because a GraphQL enum member must be a valid name and a database enum value need not be: 'in progress' and '2xl' are both legal in Postgres and neither is a legal GraphQL enum value.

The stub resolvers throw

users: t.field({
  type: ['Users'],
  nullable: false,
  resolve: () => {
    throw new Error('Not implemented: resolve users. Return the rows.');
  },
}),

Not an empty array. A caller reading [] cannot tell "no rows" from "nobody wrote this yet".

Options

Option	Default	What it does
path	outDir	Where the modules are written
naming.routerSuffix	none	Appended to each module name and type name
naming.procedureCase	none	Casing for file names and identifiers